MIAMI — Before Hurricane Ian slammed into Florida’s southwest coast with 155 mph winds, it went through two separate bursts of so-called “rapid intensification” when a cyclone’s top wind speeds rise by 35 mph in a single day.
This process took Ian from tropical storm to Category 4 monster in 36 hours. It’s a dangerous phenomenon that climate change may make more common in future hurricane seasons.
“It’s too early to say exactly how climate change affected this one storm,” said Kieran Bhatia, a climate researcher at Princeton University who studies hurricanes. “But, on average, we’ve seen multiple studies that show the conditions in the North Atlantic basin are providing more opportunities for storms to intensify.”
Climate change makes rapid intensification more likely
There are three main factors that lead to rapid intensification: warm waters, stable atmospheric conditions, and high humidity in the middle layers of the atmosphere. All three will be exacerbated by climate change.
“One can anticipate these kinds of events will happen more and more often in the future,” said Karthik Balaguru, a climate scientist at the Pacific Northwest National Laboratory who studies ocean warming and tropical cyclones.
Hurricanes gather their strength from the heat stored in ocean waters. The warmer the surface temperature of the sea, the more fuel storms have to feed on. The temperature of the water deeper down matters, too. Hurricane winds tend to churn up the sea, causing the water at the surface to mix with deeper layers of water. If the deep water is cold, it can slam the breaks on rapid intensification. But if the deep water is also warm, it will add more fuel to the storm.
Oceans have absorbed about 90% of the heat from man-made climate change. A third of that heat has gone into surface waters, which have warmed, on average, 0.14 degrees Fahrenheit per decade since 1901, according to the National Oceanic and Atmospheric Administration (NOAA).
The rest of the heat is stored in deeper waters, which have become a hidden reservoir of fuel for cyclones.
“Looking at the surface, you only see a small change in temperature,” said Balaguru. “But it takes a lot of energy to be stored in the ocean to change the surface temperature.”